A microelectronic device comprises blocks, contact structures, filled vias, and a base structure. The blocks each have a vertically alternating sequence of conductive structures and insulative structures arranged in tiers. Each block comprises a forward staircase structure and a reverse staircase structure. The contact structures are on steps of the forward staircase structure of a first of the blocks and on additional steps of the reverse staircase structure of a second of the blocks horizontally neighboring the first of the blocks. The filled vias extend through portions of the first of the blocks within horizontal boundaries of the reverse staircase structure of the first of the blocks and extend through portions of the second of the blocks within horizontal boundaries of the forward staircase structure of the second of the blocks. The base structure underlies the blocks and comprises transistors coupled to the filled vias.